Encoder Delay Adjustment

a delay adjustment and encoder technology, applied in the field of encoder delay adjustment, can solve the problems of increase in algorithmic time delay by look-ahead time duration, and achieve the effect of increasing algorithmic time delay and decreasing algorithmic time delay

Inactive Publication Date: 2008-05-01
NOKIA CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

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Benefits of technology

[0003]An aspect of the present invention provides methods and apparatus for adjusting an algorithmic time delay of a signal encoder. An input signal, e.g., a speech signal, is sampled at a predetermined sampling rate. A processing module processes a segment of input signal consisting of a current frame and a segment of future signal, typically referred as a look-ahead segment. When look-ahead operation is initiated, the algorithmic time delay is increased by the look-ahead time duration. When look-ahead operation is terminated, the algorithmic time delay is decreased by the look-ahead time duration. A set of input signal samples is aligned in accordance with the algorithmic time delay, and an output signal that is representative of the set of signal samples is formed.

Problems solved by technology

When look-ahead operation is initiated, the algorithmic time delay is increased by the look-ahead time duration.

Method used

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Embodiment Construction

[0013]In the following description of the various embodiments, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration various embodiments in which the invention may be practiced. It is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention.

[0014]FIG. 1 shows a buffering structure of an input signal for a signal encoder that is configured for a look-ahead operation in accordance with an embodiment of the invention. With an embodiment of the invention, the signal encoder utilizes an adaptive multi-rate (AMR) speech algorithm. For example, the AMR speech coder (in accordance with 3GPP TS 26.290) supports a plurality of bit-rates including bit-rate modes of 12.2 kbits / sec, 10.2 kbits / sec, 7.95 kbits / sec, 7.40 kbits / sec, 6.70 kbits / sec, 5.90 kbits / sec, 5.15 kbits / sec, and 4.75 kbits / sec. FIG. 1 shows a buffering ...

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Abstract

The present invention provides methods and apparatus for adjusting an algorithmic time delay of a signal encoder. An input signal is sampled at a predetermined sampling rate. When look-ahead operation is initiated, the algorithmic time delay is increased by the look-ahead time duration. When look-ahead operation is terminated, the algorithmic time delay is decreased by the look-ahead time duration. A set of input signal samples is aligned in accordance with the algorithmic time delay, and an output signal that is representative of the set of signal samples is formed. A first signal segment is added to an input signal waveform when the look-ahead operation is initiated, and a second signal segment is removed from the input signal waveform when the look-ahead operation is terminated. Pointers that point to a beginning of the current frame and to new input signal samples are adjusted when the operational mode changes.

Description

FIELD OF THE INVENTION[0001]The present invention relates to adjusting an algorithmic time delay for a signal encoder, which may function in a speech codec.BACKGROUND OF THE INVENTION[0002]End-to-end time delay often affects the overall quality service of a communication system. For example, with speech communications, the time delay should be short enough to allow natural conversation. While target one-way delay is recommended to be less than 150 ms, generally it has been assumed that one-way delays up to 200 ms can be expected to provide high level of interactivity causing no degradation to the subjective quality. With certain assumptions delays up to 400 ms are considered acceptable. However, although pushing one-way delays clearly below 200 ms cannot be expected to provide a substantial improvement in subjective quality of service, many communications systems are designed and thus operating in the delay range 200 to 400 ms. Furthermore, packet switched networks, e.g., IP based n...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G10L19/12
CPCG10L19/22
Inventor LAKANIEMI, ARIKIRLA, OLLI
Owner NOKIA CORP
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